“A number of years ago, a member was injured on Eaglehawk Road at a car breath testing site where a vehicle struck him when he was doing preliminary breath testing on the side of the road,” he said.

“The injury in the end led to him leaving the police force.”

Since that incident in the early 2000s, Sergeant Annand said numerous police officers had narrowly avoided being struck by drivers who neglected to slow down when they saw an emergency services vehicle parked on the shoulder.

“We’ve had members that have had to jump out of the way and yell to get drivers’ attention because cars are coming through too quickly,” he said.

“A common one for us is when we’re doing car breath testing sites, which are normally done on the roadway, and cars are approaching, the police car will have its lights on and have the cones out and the police officer’s at a protected area in front and they don’t slow down,” he said.

“In the past we would need to prove careless or dangerous driving but now there’s a specific offence for failing to slow down.”

“Certainly when we’re working in a high traffic area or even at night time, cars coming past that don’t slow down are really very dangerous,” he said.

“You’ve got to be very aware of your environment and what’s going on around you and it does take a little bit of the focus off the scene.”

However, Mr Jackson also raised concerns about whether drivers suddenly stopping could pose a risk in itself.

“I drive a truck for a living and it can be quite difficult and really hazardous to have to slow down to 40km/h in an instant, basically, without warning, so yes it could cause some hazards for the motorists themselves,” he said.

But Sergeant Annand said while people “suddenly seeing a police car and jamming on the brakes” could lead to a “concertina effect with traffic travelling behind”, reducing the hazard was a matter of “paying attention to what’s happening immediately in front of you but also what’s coming up in the distance and not just looking at the car in front of you”.

Associate Professor Stuart Newstead of Monash University's accident research centre, said educating heavy-vehicle drivers to safely slow down at emergency scenes was critical to the policy's success.

"The intent of the changes is very good but we need to be educating motorists extensively on the new rules ... a small segment on television or an article in the newspaper is not enough. There needs to be major publicity about it," Associate Professor Newstead said.

"This is particularly important for heavy-vehicle drivers because if they don't know to slow down they can take a lot of people out with them which can obviously have very serious outcomes for everyone involved."

Road Safety Minister Luke Donnellan said while most drivers already slowed down when approaching a roadside accident, the new rule made this a required standard.

“Drivers will now have to safely slow down as they approach a roadside incident, so that they pass at 40km/h,” he said.

“After passing the vehicle, drivers should not increase speed again until reaching a safe distance from the scene, so that emergency workers can do their job without fear of being hit by passing traffic.”

Mr Donnellan said there would be an extensive campaign to ensure road users were aware of the change.